1. Field of the Invention
The invention relates to an optical device and a stabilizing method for optical elements thereof, and more particularly to an optical device and a stabilizing method for optical elements thereof by utilizing a protrusion to increase structural stability of elements of the optical device.
2. Description of the Related Art
When a camera is turned on, a lens may stretch out to receive light. In such a structure, lens groups are generally designed to be rotatable between a working position and a withdrawing position wherein the lens group in the working position enables an image to be formed on an image sensor. When the camera is turned off, the lens groups move to retract into the camera by overlapping with each other. As cameras are required to be lighter and slimmer, the entire structure is therefore required to be more compact. Thus, the lens groups are designed to be rotatable to have a compact structure after the lane groups overlap with each other. When the camera is turned on, the lens groups are rotated to their working position so that light can pass through the lens groups to form an image on the image sensor. When the camera is turned off, the lens groups are rotated to their withdrawing position to facilitate their accommodation. The structure of cameras is disclosed in Taiwan patent publication no. 201232027 and Taiwan patent publication no. 2013160691.
When the lens groups move from the withdrawing position to the working position, an inner frame carrying lens is positioned by abutting an outer frame so that light can pass through the lens groups to form an image on the image sensor. Referring to FIG. 1, a conventional optical lens includes a rotatable gear 10 which engages with a driving gear 22 disposed on an inner frame 20. The inner frame 20 carries a lens group (not shown) and is rotatably disposed on an outer frame 30. The rotatable gear 10 rotates to move the inner frame 20 between a working position and a withdrawing position. FIG. 1 shows the inner frame 10 in the working position. The inner frame 20 has a first positioning surface 24, and the outer frame 30 has a second positioning surface 34 corresponding to the first positioning surface 24. When the inner frame 20 moves from the withdrawing position to the working position shown in FIG. 1, the first positioning surface 24 abuts the second positioning surface 34 for positioning the inner frame 20.
Referring to FIGS. 2 to 4, as the first positioning surface 24 and the second positioning surface 34 are flat surfaces, the contact position of the first positioning surface 24 and the second positioning surface 34 depends on the shape and tolerance of the inner frame 20 and the outer frame 30, which is possibly on upper side (as shown in FIG. 2), on lower side (as shown in FIG. 3) or uncertain (as shown in FIG. 4). The uncertain contact position may cause uncertain position of the inner frame 20 when the inner frame 20 moves to the working position, which may causes unstable optical property of the optical lens.